The subject matter disclosed herein relates to raw material treatment. More specifically, disclosed embodiments of the invention relate to the drying of feedstock by using steam from various plant components.
Fossil fuels, such as coal or petroleum, may be gasified for use in the production of electricity, chemicals, synthetic fuels, or for a variety of other applications. Gasification involves the incomplete combustion of a carbonaceous fuel with limited oxygen at a very high temperature to produce syngas, a fuel containing carbon monoxide and hydrogen, which enables higher efficiency and cleaner emissions than the fuel in its original state.
Different carbonaceous fuels may be gasified with varying success. That is, a lower moisture content value generally indicates that a fuel is more easily combustible and more efficiently gasified. The moisture content value of a material is a measure of the amount of water present in the material. For example, petcoke, which is produced from cracking petroleum, has relatively low moisture content and, therefore, is easily gasified. In contrast, low rank coals and biomass may have high moisture content and are, therefore, difficult to gasify. In some instances, biomass such as corn stalks and switchgrass may contain so much moisture that it becomes too inefficient to gasify the fuel. In addition, high moisture in fuels degrades flowability and causes frequent plugging during handling and conveyance. Possible nuisances include fouling of baghouses and bridging of nozzles. Sufficient moisture must be removed so that the fuel may be reliably conveyed to the reaction furnace. The moisture in the fuel may be removed through heating. However, the energy required for heating the fuel may be cost-prohibitive. Accordingly, it may be desirable to develop methods and systems for more efficiently drying solid fuels, including low rank coals and biomass.